Making Outlook faster yet smaller, so email messages load quicker but take up less storage.

better management features so IT pros can apply patches faster, use their other Microsoft PC security and management tools with Office and so on.

No changes to macros. The update won't impact all those important, programmed Excel spreadsheets or Word documents turned into forms.

This will also be the first version of Office for Windows designed from the get-go for tablets and touchscreens, although it's not clear how much of the new tablet look-and-feel these preview versions will show off. In the blog post, Microsoft's Kirk Koenigsbauer didn't mention touch and warned, "This early build doesn’t yet contain all the features we’re planning to ship in the final product."

Part of the bargain when you pay for the cloud is that you automatically get the latest upgrades with no effort on your part. Microsoft updates its cloud and poof!, you have the latest.

But with Office 365, many business opt to get the downloadable version of Office to install on their corporate PCs, too. So they'll want to see, test and offer feedback on Office 2016 before they take on the task of installing it on everyone's PCs, and, perhaps, buying new PCs and tablets to run it.

The blog post didn't share any pictures of Office 2016, but last month Microsoft offered a peek at some of the new touch-friendly Office Apps that will be included for free on smaller Windows 10 devices. Seems likely the full-blown paid-for Office 2016 versions will look similar.